The present invention relates to a driving depth adjusting mechanism for a nailer or a comparable fastening tool which is capable of adjusting the driving depth of a nail or a comparable fastening member without using a dedicated or special adjusting tool such as a spanner.
A method for adjusting the driving depth of a nailer or a comparable fastening tool is conventionally known. In this case, the driving depth is expressed by a height from the head of a nail (or a fastening member) struck into a board or a comparable base material by a nailer (or a comparable fastening tool) to the surface of the board material. For example, the protruding length adjustment for a driver blade of a nailer or a comparable fastening tool is feasible by adjusting a distance between the distal end of a push lever and the distal end of the driver blade under the condition that the push lever is placed on the surface of the board material into which the nail or the fastening member is struck or driven while the driver blade is positioned at its bottom dead center.
FIG. 11 shows a nail striking operation of a nailer equipped with a conventional driving depth adjusting mechanism. To implement the nail striking operation, a push lever 1 is first placed on the surface of a board material 3 into which a nail 16 is driven. A spring 2 resiliently urges the push lever 1 downward. When raised by a user, the push lever 1 can shift upward against a depression or resilient force of the spring 2. A shaft 4 shifts upward together with the push lever 1. A bolt 6, screwed into a main body 5 at a predetermined upper portion above the shaft 4, restricts the reachable uppermost position of the shaft 4 shifting in the up-and-down direction. In other words, a protruding length S of a driver blade 7, in the condition that the driver blade 7 is positioned at a bottom dead center, is restricted by the position of bolt 6. The protruding length S determines the driving depth of the nailer.
FIG. 12 explains the details of the driving depth adjustment performed by a user. A nut 8 is engaged with the bolt 6. The nut 8 and a female thread of the main body 5 cooperatively constitute a double nut engagement for securely fixing the bolt 6 with respect to the main body 5. First, the user loosens the nut 8 by using a spanner or the like. With this loosening operation, the fixation of the bolt 6 to the main body 5 is released. Next, the user rotates the bolt 6 in either direction to change the distance between a bolt head 6a and the main body 5. Then, the user fastens the nut 8 by using the spanner or the like to again establish the double nut engagement for securely fixing the bolt 6. When the user performs a nail striking operation after the position of the bolt head 6a is changed, the reachable uppermost position of the push lever 1 changes. The protruding length S of the driver blade 7 also changes. Accordingly, the driving depth of the nailer changes.
According to the above-described conventional driving depth adjusting mechanism of a nailer, the female thread of the main body 5 and the nut 8 cooperatively constitute the double nut engagement for securely fixing the bolt 6. This arrangement forces the user to frequently use the spanner or any other comparable adjusting tool for loosening or fastening the bolt 6. It takes a significantly long time for each adjustment of the driving depth of a nailer. It is needless to say that the user must always keep the spanner or the like.
An object of the present invention is to provide a driving depth adjusting mechanism for a nailer which assures improved operability in the driving depth adjustment and allows a user to implement the driving depth adjustment without using a spanner or any other comparable adjusting tool for loosening or fastening the bolt.
In order to accomplish this and other related objects, the present invention provides a driving depth adjusting mechanism for a nailer or a fastening tool having a main body and a push lever. The main body is equipped with a driver blade for driving a nail or a fastening element and an ejecting section from which the nail of the fastening element is pushed out. The push lever, extending along the ejecting section, reciprocates in an axial direction of the driver blade for controlling the driving operation. The driving depth adjusting mechanism includes a bolt screwed into a hole of the main body for regulating an uppermost position of the push lever during a striking operation of the nail or the fastening element, a knob having an inner space for accommodating the bolt, and a spline coupling provided between the bolt and the knob for transmitting a rotational motion of the knob to the bolt and for allowing the knob to slide in the axial direction.
Preferably, the driving depth adjusting mechanism further comprises a stopper for restricting a mutual rotation between the knob and the main body, and an elastic member for elastically urging the knob in a direction for restricting the mutual rotation between the knob and the main body.
Preferably, the spline coupling is constituted by a hexagonal inner wall of the knob and a hexagonal head of the bolt.
Preferably, the knob is a resin-made member.
Preferably, the knob has a projection in the inner space for preventing the bolt from being pulled out.